Some of the existing hearing aids have multiple modes of operation. The different modes of operation enable the hearing aid to meet as good as possible various general and/or specific needs of the user in different situations or environments. As an example, directionality makes it possible for a hearing aid to “focus” on a sound source, such as a speaking person, located e.g. in front of the wearer of the hearing aid. Thereby, possibly disturbing sounds coming from the sides and back of the wearer will have a limited influence on the wearer's perception of sound from a source in front of him/her. One or more modes of operation may therefore include such beam-forming signal processing.
As another example, a specific acoustical environment may require the use of specific noise suppression and/or other specific signal processing which can therefore be selected as a program or mode of operation. Further, in one or more modes of operation, the hearing aid may make use of a telecoil for receiving audio information from an electromagnetic field.
Since it is quite inconvenient for a hearing impaired person to manually switch between different modes of operation in dependence of his/her needs, several attempts have been made to develop efficient methods for automatically selecting “the best” mode of operation as the listening environment or conditions changes.
Modern hearing aids feature signal processing which is automatically adjusted either in accordance with pre-programmed settings or by continuous, incremental adjustments that are believed to improve the speech intelligibility or listening comfort in the given environment. Often so-called “soft-switching” between modes or states is used in order not to create a sudden and disturbing change in sound quality.
Also, many hearing aids offer the opportunity to force the aid into a certain mode based on the choice of the user. A signal is added into the amplified audio signal to confirm the change of mode. The signal is normally a series of beeps or the like. It has previously been suggested that such signal could be recordings of voice messages.
One of the pitfalls of automatic switching of modes is that the system switches into a mode or state that is not seen as an improvement by the user. It is not given that all users have the same demands in situations that appear similar to the recognition system and it may not be possible to discover that during the fitting process.